What do you feel is the best advice you could give to someone under 30 years old?

I'm not 30 yet, but here's something I've learned lately. Stop living based on "standards" and on "trends". Every single person is different. Don't expect to live your life by things one must achieve at a certain age. There's no such a thing. Well of course if you want to be a top sporter you might have some limitations, but life in general doesn't happen that way.